The healing process of bone is a complicated cascade of events. Rapid and diverse events are activated by a fracture or osteotomy of a bone in order to limit the loss of blood and initiate cellular migration resulting in repair. Current concepts suggest that these cellular events are controlled to a large part by growth factors, low-molecular-weight glycoproteins, inducing migration, proliferation and differentiation of an appropriate subset of cells in the site of the fracture.
Despite of the amount of known details the bone healing as a whole is still a poorly understood process. Based on this lacking information and experimental data research has revealed several methods to enhance bone growth, such as mechanical stimulation, electromagnetic fields, low-intensity ultrasound, osteoconductive materials, for instance hydroxyapatite, tricalcium phosphate, bioactive glass etc., and osteoinductive materials, such as growth factors.
Osteoinduction is a process where any substance, stimulation etc. starts or enhances a cellular response resulting in a bone formation process. Growth factors are a wide group of molecules known to possess this effect. According to the current knowledge, bone morphogenetic proteins (BMP) are the only growth factors known to induce bone formation heterotopically by inducing undifferentiated mesenchymal cells to differentiate into osteoblasts. Consequently, several BMPs are shown to boost the bone healing process when supplementary doses are given.
For example, U.S. Pat. No. 5,725,491 discloses a biodegradable film dressing as a delivery system of various therapeutic agents, such as BMPs. The therapeutic agent is delivered from the film dressing in a certain and controlled release rate. However, BMPs are produced by genetic engineering, which is still rather expensive. Also, delivery of a correct dose of BMPs is difficult and presents great challenges for the future.
Known materials, methods and implants are expensive and exploitation of such materials, methods and implants is constrained.